Line Chart New

import { useMemo, useState, type KeyboardEvent, type PointerEvent } from 'react';
import { ChartFrame, Legend, SERIES_COLORS, Segmented, Tooltip, fmt, niceMax, scale, smoothPath, useInView, useToggleSet, useWidth } from './chart-utils';

export type LineSeries = { name: string; color?: string; values: number[] };

export type LineChartProps = {
  labels: string[];
  series: LineSeries[];
  height?: number;
  prefix?: string;
  /** Changing this key replays the draw-in animation (e.g. on range change). */
  animationKey?: string | number;
};

const PAD = { t: 12, r: 12, b: 26, l: 40 };

export function LineChart({ labels, series, height = 260, prefix = '', animationKey }: LineChartProps) {
  const { ref: wrap, w } = useWidth<HTMLDivElement>();
  const { ref: view, seen } = useInView<HTMLDivElement>();
  const { hidden, toggle } = useToggleSet();
  const [hover, setHover] = useState<number | null>(null);

  const colored = series.map((s, i) => ({ ...s, color: s.color ?? SERIES_COLORS[i % SERIES_COLORS.length] }));
  const visible = colored.filter((s) => !hidden.has(s.name));
  const max = niceMax(Math.max(1, ...visible.flatMap((s) => s.values)));
  const x = scale(0, labels.length - 1, PAD.l, w - PAD.r);
  const y = scale(0, max, height - PAD.b, PAD.t);
  const ticks = [0, 0.25, 0.5, 0.75, 1].map((f) => f * max);
  const labelEvery = Math.ceil(labels.length / Math.max(2, Math.floor(w / 70)));

  const pick = (clientX: number, el: Element) => {
    const r = el.getBoundingClientRect();
    const i = Math.round(((clientX - r.left - PAD.l) / (w - PAD.l - PAD.r)) * (labels.length - 1));
    setHover(Math.max(0, Math.min(labels.length - 1, i)));
  };
  const onKey = (e: KeyboardEvent) => {
    if (e.key === 'ArrowRight') setHover((h) => Math.min(labels.length - 1, (h ?? -1) + 1));
    else if (e.key === 'ArrowLeft') setHover((h) => Math.max(0, (h ?? labels.length) - 1));
    else if (e.key === 'Escape') setHover(null);
  };

  return (
    <div ref={view} className="space-y-3">
      <Legend items={colored} hidden={hidden} onToggle={toggle} />
      <div ref={wrap} className="relative w-full">
        <svg
          width={w}
          height={height}
          className="block touch-pan-y outline-none"
          tabIndex={0}
          role="img"
          aria-label={`Line chart of ${visible.map((s) => s.name).join(' and ')}. Use arrow keys to read values.`}
          onPointerMove={(e: PointerEvent<SVGSVGElement>) => pick(e.clientX, e.currentTarget)}
          onPointerLeave={() => setHover(null)}
          onKeyDown={onKey}
          onBlur={() => setHover(null)}
        >
          <defs>
            {colored.map((s, i) => (
              <linearGradient key={i} id={`lc-g-${i}`} x1="0" y1="0" x2="0" y2="1">
                <stop offset="0%" stopColor={s.color} stopOpacity="0.22" />
                <stop offset="100%" stopColor={s.color} stopOpacity="0" />
              </linearGradient>
            ))}
          </defs>
          {ticks.map((t) => (
            <g key={t}>
              <line x1={PAD.l} x2={w - PAD.r} y1={y(t)} y2={y(t)} stroke="rgba(255,255,255,0.06)" strokeDasharray={t === 0 ? undefined : '3 4'} />
              <text x={PAD.l - 8} y={y(t)} dy="0.32em" textAnchor="end" className="fill-ink-500 font-mono text-[10px]">
                {fmt(t, prefix)}
              </text>
            </g>
          ))}
          {labels.map((l, i) =>
            i % labelEvery === 0 ? (
              <text key={i} x={x(i)} y={height - 6} textAnchor="middle" className="fill-ink-500 font-mono text-[10px]">
                {l}
              </text>
            ) : null,
          )}
          {colored.map((s, si) => {
            if (hidden.has(s.name)) return null;
            const pts = s.values.map((v, i) => [x(i), y(v)] as [number, number]);
            const line = smoothPath(pts);
            return (
              <g key={`${s.name}-${animationKey}-${w}`}>
                <path d={`${line} L${x(labels.length - 1)},${y(0)} L${x(0)},${y(0)} Z`} fill={`url(#lc-g-${si})`} className="transition-opacity duration-700" style={{ opacity: seen ? 1 : 0, transitionDelay: '400ms' }} />
                <path
                  d={line}
                  fill="none"
                  stroke={s.color}
                  strokeWidth={2.2}
                  strokeLinecap="round"
                  pathLength={1}
                  strokeDasharray="1"
                  style={{ strokeDashoffset: seen ? 0 : 1, transition: 'stroke-dashoffset 1.2s cubic-bezier(0.16,1,0.3,1)', transitionDelay: `${si * 120}ms` }}
                />
              </g>
            );
          })}
          {hover !== null && (
            <g>
              <line x1={x(hover)} x2={x(hover)} y1={PAD.t} y2={height - PAD.b} stroke="rgba(255,255,255,0.18)" strokeDasharray="3 3" />
              {visible.map((s) => (
                <circle key={s.name} cx={x(hover)} cy={y(s.values[hover])} r={4.5} fill="#0b0c0e" stroke={s.color} strokeWidth={2} />
              ))}
            </g>
          )}
        </svg>
        {hover !== null && visible.length > 0 && (
          <Tooltip x={x(hover)} y={Math.min(...visible.map((s) => y(s.values[hover])))} w={w}>
            <p className="mb-1 font-mono text-[10px] text-ink-400">{labels[hover]}</p>
            {visible.map((s) => (
              <p key={s.name} className="flex items-center gap-2 whitespace-nowrap text-ink-100">
                <span className="h-1.5 w-1.5 rounded-full" style={{ background: s.color }} />
                <span className="text-ink-400">{s.name}</span>
                <span className="ml-auto pl-3 font-mono tabular-nums">{prefix + s.values[hover].toLocaleString('en-US')}</span>
              </p>
            ))}
          </Tooltip>
        )}
      </div>
    </div>
  );
}

const RANGES = { '7D': 7, '30D': 30, '90D': 90 } as const;
type Range = keyof typeof RANGES;

function wave(n: number, base: number, amp: number, seed: number) {
  return Array.from({ length: n }, (_, i) => Math.round(base + amp * Math.sin(i / 3.2 + seed) + amp * 0.6 * Math.sin(i / 1.3 + seed * 2) + i * (base / n) * 0.6));
}

export function LineChartDemo() {
  const [range, setRange] = useState<Range>('30D');
  const data = useMemo(() => {
    const n = RANGES[range];
    const labels = Array.from({ length: n }, (_, i) => {
      const d = new Date(2026, 9, 30 - (n - 1 - i));
      return d.toLocaleDateString('en-US', { month: 'short', day: 'numeric' });
    });
    return { labels, series: [{ name: 'Revenue', values: wave(n, 4200, 900, 1) }, { name: 'Expenses', values: wave(n, 2600, 500, 4) }] };
  }, [range]);
  const total = data.series[0].values.reduce((a, b) => a + b, 0);
  return (
    <ChartFrame
      title="Revenue vs expenses"
      sub={
        <span>
          <span className="font-mono text-base tabular-nums text-ink-50">${total.toLocaleString('en-US')}</span> <span className="text-emerald-400">↑ 12.4%</span> this period
        </span>
      }
      right={<Segmented value={range} options={Object.keys(RANGES) as Range[]} onChange={setRange} />}
    >
      <LineChart labels={data.labels} series={data.series} prefix="$" animationKey={range} />
    </ChartFrame>
  );
}

import { useEffect, useRef, useState, type ReactNode } from 'react';
import { cn } from '@/lib/cn';

export const SERIES_COLORS = ['#38bdf8', '#a78bfa', '#34d399', '#fbbf24', '#f472b6'];

export const reducedMotion = () => typeof window !== 'undefined' && window.matchMedia('(prefers-reduced-motion: reduce)').matches;

/** Becomes true once the element scrolls into view (or immediately under reduced motion). */
export function useInView<T extends Element>(threshold = 0.25) {
  const ref = useRef<T>(null);
  const [seen, setSeen] = useState(false);
  useEffect(() => {
    if (reducedMotion()) return setSeen(true);
    const el = ref.current;
    if (!el) return;
    const io = new IntersectionObserver(([e]) => e.isIntersecting && (setSeen(true), io.disconnect()), { threshold });
    io.observe(el);
    return () => io.disconnect();
  }, [threshold]);
  return { ref, seen };
}

/** Tracks the rendered width of an element so SVG charts can draw at true pixel size. */
export function useWidth<T extends Element>(fallback = 600) {
  const ref = useRef<T>(null);
  const [w, setW] = useState(fallback);
  useEffect(() => {
    const el = ref.current;
    if (!el) return;
    const ro = new ResizeObserver(([e]) => setW(Math.max(200, Math.round(e.contentRect.width))));
    ro.observe(el);
    return () => ro.disconnect();
  }, []);
  return { ref, w };
}

export const scale = (d0: number, d1: number, r0: number, r1: number) => (v: number) => r0 + ((v - d0) / (d1 - d0 || 1)) * (r1 - r0);

/** Nice upper bound for an axis. */
export function niceMax(v: number) {
  if (v <= 0) return 1;
  const p = Math.pow(10, Math.floor(Math.log10(v)));
  const n = v / p;
  return (n <= 1 ? 1 : n <= 2 ? 2 : n <= 2.5 ? 2.5 : n <= 5 ? 5 : 10) * p;
}

/** Smooth monotone-ish path through points (Catmull-Rom → Bézier, tension 0.5). */
export function smoothPath(pts: [number, number][]) {
  if (pts.length < 2) return '';
  let d = `M${pts[0][0]},${pts[0][1]}`;
  for (let i = 0; i < pts.length - 1; i++) {
    const p0 = pts[i - 1] ?? pts[i];
    const p1 = pts[i];
    const p2 = pts[i + 1];
    const p3 = pts[i + 2] ?? p2;
    const c1x = p1[0] + (p2[0] - p0[0]) / 6;
    const c1y = p1[1] + (p2[1] - p0[1]) / 6;
    const c2x = p2[0] - (p3[0] - p1[0]) / 6;
    const c2y = p2[1] - (p3[1] - p1[1]) / 6;
    d += ` C${c1x},${c1y} ${c2x},${c2y} ${p2[0]},${p2[1]}`;
  }
  return d;
}

export const fmt = (v: number, prefix = '') => prefix + (Math.abs(v) >= 1000 ? (v / 1000).toFixed(v >= 10000 ? 0 : 1) + 'k' : String(Math.round(v)));

export function Legend({ items, hidden, onToggle }: { items: { name: string; color: string }[]; hidden: Set<string>; onToggle: (name: string) => void }) {
  return (
    <div className="flex flex-wrap gap-1.5">
      {items.map((s) => {
        const off = hidden.has(s.name);
        return (
          <button
            key={s.name}
            onClick={() => onToggle(s.name)}
            aria-pressed={!off}
            className={cn('focus-ring flex items-center gap-1.5 rounded-full border px-2.5 py-1 text-xs transition-all', off ? 'border-white/5 text-ink-500' : 'border-white/10 bg-white/[0.03] text-ink-200 hover:bg-white/[0.06]')}
          >
            <span className="h-2 w-2 rounded-full transition-opacity" style={{ background: s.color, opacity: off ? 0.3 : 1 }} />
            {s.name}
          </button>
        );
      })}
    </div>
  );
}

export function useToggleSet() {
  const [hidden, setHidden] = useState<Set<string>>(new Set());
  const toggle = (k: string) =>
    setHidden((h) => {
      const n = new Set(h);
      if (n.has(k)) n.delete(k);
      else n.add(k);
      return n;
    });
  return { hidden, toggle };
}

export function Tooltip({ x, y, w, children }: { x: number; y: number; w: number; children: ReactNode }) {
  const left = Math.min(Math.max(x, 70), w - 70);
  return (
    <div className="pointer-events-none absolute z-10 -translate-x-1/2 -translate-y-full rounded-xl border border-white/10 bg-ink-850/95 px-3 py-2 text-xs shadow-pop backdrop-blur" style={{ left, top: y - 10 }}>
      {children}
    </div>
  );
}

export function Segmented<T extends string>({ value, options, onChange }: { value: T; options: T[]; onChange: (v: T) => void }) {
  return (
    <div className="flex rounded-lg bg-white/[0.04] p-0.5 ring-1 ring-white/5">
      {options.map((o) => (
        <button key={o} onClick={() => onChange(o)} className={cn('focus-ring rounded-md px-2.5 py-1 text-xs font-medium transition-all', value === o ? 'bg-ink-800 text-ink-50 shadow-hairline' : 'text-ink-400 hover:text-ink-200')}>
          {o}
        </button>
      ))}
    </div>
  );
}

export function ChartFrame({ title, sub, right, children, className }: { title: string; sub?: ReactNode; right?: ReactNode; children: ReactNode; className?: string }) {
  return (
    <div className={cn('w-full rounded-2xl bg-ink-900 p-4 shadow-card sm:p-5', className)}>
      <div className="mb-4 flex flex-wrap items-start justify-between gap-3">
        <div className="min-w-0">
          <p className="text-sm font-medium text-ink-100">{title}</p>
          {sub && <div className="mt-0.5 text-xs text-ink-500">{sub}</div>}
        </div>
        {right}
      </div>
      {children}
    </div>
  );
}